stars : early-type; stars : individual : HD 191612; X-rays : individual : HD 191612; X-rays : stars
Abstract :
[en] We present the analysis of phase-resolved X-ray and optical observations of the peculiar hot star HD 191612 (Of ? p). This star is known to display line-profile variations that are recurrent with a period of 538 d and its spectrum was found to present the signature of a magnetic field. In the X-rays, it is slightly overluminous compared to the canonical L-X/L-BOL) relation and appears brighter when the optical lines are strongest. Our XMM-Newton observations further reveal that the X-ray spectrum of HD 191612 exhibits rather broad lines and is dominated by a 'cool' (0.2-0.6 keV) thermal component, two characteristics at odds with the proposed magnetic rotator model. We also report for the first time the low-level variability of the metallic (absorption/emission) lines and He ii absorptions that appear to be associated with radial-velocity shifts. Finally, we compare our results with observations of the early-type stars and discuss several possible scenarios.
Disciplines :
Earth sciences & physical geography
Author, co-author :
Nazé, Yaël ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Groupe d'astrophysique des hautes énergies (GAPHE)
Rauw, Grégor ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Groupe d'astrophysique des hautes énergies (GAPHE)
Pollock, A. M. T.
Walborn, N. R.
Howarth, I. D.
Language :
English
Title :
Towards an understanding of the Of ? p star HD 191612: phase-resolved multiwavelength observations
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